The following relates generally to wireless communication and more specifically to multiple transmission time interval (TTI) coexistence within a wireless communications system.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems. A wireless multiple-access communications system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
Wireless multiple-access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is designed to improve spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards. LTE may use OFDMA on the downlink (DL), single-carrier frequency division multiple access (SC-FDMA) on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology.
Wireless devices within an LTE or other multiple-access system may communicate with transmission time intervals (TTIs) of different durations. A TTI that is reduced relative to other TTIs may be employed to reduce the time between transmissions (e.g., between a transmission of data, a feedback response, and a retransmission). In some cases, different TTI durations may be appropriate for different UEs based on UE capabilities or channel conditions. Different UEs communicating with different TTI durations may, however, cause resource scheduling conflicts and increased system complexity.